This invention relates to a shaker conveyor and more particularly to a shaker conveyor and improved rotary drive mechanism therefor.
Conveyors are used in manufacturing and other appropriate industries as an efficient way of moving material of many different types from one place to another. A shaker conveyor is especially useful because it can transport a wide variety of materials. A shaker conveyor may even be used to transfer corrosive, high-temperature, heavy, or other difficult to transport materials from place to place. For example, hot metal castings can be transported by shaker conveyor as can particulate material or other material difficult to transport due to physical or chemical characteristics. The flexibility as to different types of materials is derived from the trough which supports the material being carried. This trough can be made of solid material resistant to heat, corrosion, or physical or chemical problems caused by the material being transported.
The trough in a shaker conveyor is moved in a longitudinal reciprocating movement in order to move the material carried thereby in a desired direction. Conventionally, the trough on a shaker conveyor is accelerated in the direction of a desired material movement in order to reach the maximum velocity and then decelerated rapidly followed by a reversal of direction so that the material thereon slides an incremental distance in the desired direction. As the trough is moving in a direction opposite to the desired direction of material movement, the material decelerates and comes to rest, and immediately begins to accelerate in the direction of desired material movement slowly so that there is little or no backward sliding of material being conveyed along the trough.
To achieve this forward motion of material with reciprocating action, there are a number of drive mechanisms which achieve this desired result. Typical of the prior art mechanisms which achieve this type of motion, are those which use rocking arms and pulling arms to achieve the desired reciprocatory motion. While this drive produces satisfactory motion, the operating elements are complicated and tend to be difficult to manufacture. The complicated elements also tend to be expensive to maintain and require substantial amount of floor space and volume which further increase costs. Additionally noise levels generated thereby tend to be excessive and undesirable.
As a further problem, the arms used to provide the reciprocating motion, have a tendency to get out of line which in turn affects the planar movement of the trough thereby putting undue stress on trough and the rest of the shaker conveyor, thereby reducing efficiency and causing further operational problems. It is extremely desirable to eliminate or reduce any vertical or lateral component of vibration of the conveyor trough. In this fashion, the energy is concentrated in the reciprocatory motion.
With the shaker conveyor drives of the prior art, such vertical or lateral components are inherent with wear on the arms, because loading of the trough causes stress and wear on the arms and arm attachments to the conventional drives and attachments for the drives. Such wear loosens the attachments and permits the lateral or vertical component of trough movement.
It is also desirable to adjust the speed of a shaker conveyor without doing major internal work on the drive mechanism. Use of arms renders such adjustments difficult.
It follows that use of arms to achieve the reciprocating movement of a shaker conveyor while necessary is inconvenient for many reasons. Therefore, it is desirable to eliminate the need for these arms in the shaker conveyor field while at the same time retaining the desirable functional aspects of the shaker conveyor.
It is well known in the prior art that the shaker conveyors and the drives used therefor are extremely effective for conveying heavy loads. However, this efficient means of conveying material is not economically justified for conveying light loads. Thus, there is a limitation on the use of these drives.
Even when drives are developed to convey light loads, it is usually necessary to have separate designs of drives for conveying lightweight and heavy duty loads. This duplication of designs and equipment is extremely expensive and adds greatly to manufacturing costs. If a shaker conveyor drive can be developed so that a shaker conveyor can be used with both lightweight and heavy loads with only minor adjustments in the trough and scaling the construction of the drive system correspondingly, it is extremely advantageous.
It is further desirable to develop a drive system for a shaker conveyor that is easily adjustable with regard to the length of the stroke. Drive systems known in the art include arm and yoke mechanisms which render the adjustment of the stroke extremely difficult. The difficulty is caused by balancing the adjustment of the fly wheel operations and the location of the yokes and arms to achieve the desired results. It thus follows that the arms are an extremely cumbersome part of the shaker conveyor of the prior art.
The advantages of simpler, more compact drive system for a shaker conveyor thus become clear.